Link between frontal collision and lateral plate extrusion: palaeomagnetic fingerprint in the Tethyan Himalaya

印度-亚洲碰撞是地球上最壮观的研究大陆碰撞地球动力学演化的“天然实验室”。该项目涉及印度压头的锋面碰撞和青藏高原挤压之间的联系。在喜马拉雅西部，古地磁资料很好地反映了造山斜的弯曲。相比之下，来自中部的数据和来自东部(不丹)的第一个结果表明，古地磁旋转与造山斜弯曲模型不相容。可以推测，青藏高原的东向挤压在喜马拉雅地区的长期变形中留下了印记，形成了一条顺时针旋转强烈的剪切带，各块体之间存在左旋走滑断层。这个模型将与GPS速度所显示的当今运动相匹配。该项目旨在通过分析约83-89°E之间的特提斯喜马拉雅东部的古地磁剩磁来检验剪切带的假说。将对西东和南北段进行采样，以获得区域旋转模式。将使用二次磁黄铁矿剩磁，这在以前的项目中被证明是可靠的结果。为了支持古地磁数据的解释，涉及到地质、年代学和地温测量工作。这一多学科的概念是基于来自德国、瑞士、奥地利、加拿大、中国和尼泊尔的科学家的合作。

The India-Asia collision is the Earth's most spectacular "natural laboratory" to study the geodynamic evolution of continental collision. The project deals with the link between frontal collision by the Indian indenter and the extrusion of the Tibetan Plateau. In the western part of the Himalaya oroclinal bending is well reflected by palaeomagnetic data. In contrast, data from the central part and a first result from the eastern part (Bhutan) indicate palaeomagnetic rotations, which are not compatible with an oroclinal bending model. It can be hypothesised that eastward extrusion of the Tibetan Plateau left its fingerprint in a long-term deformation of the Himalayan region forming a shear zone with strong clockwise block rotations and sinistral strike-slip faults between individual blocks. This model would match with present-day movements shown by GPS velocities. The proposed project aims at testing the hypothesis of a shear zone by analysing palaeomagnetic remanences in the eastern Tethyan Himalaya between ca. 83-89°E. West-east and south-north sections will be sampled to obtain a regional rotation pattern. Secondary pyrrhotite remanences will be used which proved to provide reliable results during former projects. Geological, geochronological and geothermometric work is involved in order to support the interpretation of the palaeomagnetic data. This multidisciplinary concept is based on a cooperation of scientists from Germany, Switzerland, Austria, Canada, China and Nepal.